Large scale purification of contaminated air

Abstract

A weakly ionized plasma is generated by continuous high-power microwave win a dielectric cavity positioned in a slow waveguide. Contaminated air under atmospheric pressure is exposed to the plasma within the waveguide cavity for a limited saturation time controlled by inflow at a regulated flow rate. During such limited saturation time, the contaminated air is purified by sequential ionization and recombination under an electron temperature resulting in a microwave discharge plasma dominated by atomic oxygen at a relatively high saturation density level together with atomic nitrogen at a relatively low density level.

What is claimed is: 
     
       1. Apparatus for purifying contaminated air, comprising: a source of microwave energy, a waveguide having a dielectric chamber operatively connected to said source, means conducting the contaminated air through the dielectric chamber of the waveguide for exposure to said microwave energy causing sequential ionization and recombination of the air into atomic oxygen and atomic nitrogen, and saturation control means for limiting said recombination to a saturation period during which the atomic oxygen attains a dominant saturation density level. 
     
     
       2. The apparatus as defined in claim 1 wherein said saturation control means includes pump means for regulating inflow of the contaminated air into the waveguide at a flow rate establishing said saturation period and an electron temperature therein under which the atomic nitrogen attains a density level substantially less than the dominant saturation density level of the atomic oxygen. 
     
     
       3. In a system for purifying gas within a waveguide cavity by positioning a body of the gas within said cavity; transferring microwave energy to the body of the gas positioned within the waveguide cavity for sequential ionization thereof into ionized products and recombination of the ionized products; and limiting said recombination of the ionized products, the improvement residing in said gas being contaminated air from which atomic oxygen is formed during a predetermined saturation time by said recombination of the ionized products, a source from which said waveguide cavity receives the microwave energy transferred to the body of contaminated air, means conducting flow of the body of contaminated air through the waveguide cavity for exposure thereof to the microwave energy effecting said sequential ionization and recombination of the ionized products, and saturation control means regulating said flow of the body of the contaminated air for obtaining a saturation density level of the atomic oxygen within the waveguide cavity during the predetermined saturation time as a result of said limiting of the recombination of the ionized products. 
     
     
       4. In a system having a source of microwave energy, a waveguide connected to said source, and means conducting gas through the waveguide for exposure to the microwave energy therein causing sequential ionization of the gas into ionized products and recombination of the ionized products, the improvement residing in means controlling time of said exposure of said gas to the microwave energy for limiting said recombination of the ionized products, including means for regulating inflow of the gas into the waveguide at a predetermined flow rate. 
     
     
       5. The system as defined in claim 4 wherein said gas is contaminated air from which atomic oxygen and atomic nitrogen is attained by said recombination of the ionized products, said predetermined flow rate of the gas into the waveguide establishing a dominant saturation density level of the atomic oxygen during a saturation period while the atomic nitrogen attains a density level substantially less than the saturation density level of the oxygen. 
     
     
       6. In a system of purifying contaminated air by exposure thereof to microwave energy within an electric field causing breakdown of the contaminated air into ionization products, the improvement residing in: means for controlling exposure time of the contaminated air within the electric field during which recombination of the ionization products into a discharge plasma occurs. 
     
     
       7. The improvement as defined in claim 6, wherein said means for controlling exposure time includes: means regulating inflow of the contaminated air into the electric field at a predetermined flow rate for limiting said recombination of the ionization products.